Hip Crunch (knees bent)
- Target muscle
- Iliopsoas, Rectus Abdominis
- Synergist muscles
- Adductor Brevis, Adductor Longus, Obliques, Pectineous, Sartorius, Tensor Fasciae Latae
- Equipment
- Body weight
- Body part
- Waist
- Type
- Strength
The hip crunch with knees bent is a bodyweight core exercise that targets the hip flexors (iliopsoas) and the abs (rectus abdominis). Performed lying on your back with knees bent, you curl your knees toward your chest while lifting your hips off the floor, also recruiting the obliques, hip adductors, sartorius, and tensor fasciae latae. It's a beginner-friendly way to train the lower abs and hip flexors without any equipment.
How to do the Hip Crunch (knees bent)
- 1Lie flat on your back on a mat with your arms at your sides, palms down for stability.
- 2Bend your knees to roughly 90 degrees and lift your feet so your thighs point straight up toward the ceiling.
- 3Brace your core and press your lower back gently into the floor to remove any arch.
- 4Curl your knees toward your chest, using your abs to roll your hips up and off the mat.
- 5Lift your hips a few inches as your knees travel toward your face, keeping the bend in your knees fixed.
- 6Pause briefly at the top, focusing on squeezing the abs and hip flexors.
- 7Lower your hips back to the mat slowly under control until your thighs return to vertical.
- 8Complete your reps without letting your feet touch the floor between repetitions.
Form tips
- Drive the movement by curling your pelvis toward your ribs, not by swinging your legs with momentum.
- Keep the knee angle constant throughout the rep so the work stays in the abs and hip flexors.
- Exhale as you lift your hips and inhale as you lower, keeping your core braced the whole time.
- Press your palms lightly into the mat for support, but avoid pushing hard enough to launch the hips up.
- Move slowly on the way down — the lowering phase is where much of the abdominal tension lives.
Common mistakes
- Using momentum to swing the legs up, which shifts work away from the abs and hip flexors and makes the rep easier than it looks.
- Pushing hard through the hands to throw the hips off the floor, which removes tension from the core.
- Letting the lower back arch off the mat, which loses abdominal bracing and can strain the spine.
- Yanking the knees too far toward the face and rounding the neck, straining the cervical spine.
- Dropping the hips back down quickly instead of lowering under control, wasting the most productive part of the rep.
Frequently asked questions
What muscles does the hip crunch with knees bent work?
It primarily works the hip flexors (iliopsoas) and the abs (rectus abdominis), with the obliques, hip adductors, pectineus, sartorius, and tensor fasciae latae assisting as synergists.
Is the hip crunch good for beginners?
Yes. It's a bodyweight movement with no equipment, and the bent-knee position shortens the lever so it's easier to control than straight-leg variations. Start with a small hip lift and add range as your core gets stronger.
How many sets and reps should I do?
For most lifters, 2 to 4 sets of 10 to 20 controlled reps works well. Stop short of letting your form break down or your lower back arching, and add reps before adding tempo tricks.
Where should I feel this exercise?
You should feel it in your lower abs and the front of your hips (the hip flexors). If you mainly feel it in your neck or lower back, slow down, reduce the range, and focus on curling the hips rather than swinging the legs.
